Remove unnecessary friend declarations from qevent.h.

Change-Id: Iec35b94f3898004850a076d4760d675248246ea7
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
qpa: Merge qwidget_qpa.cpp into qwidget.cpp

Change-Id: I8424ec7290b366f4c76999a956fce1428fc56626
Reviewed-by: Paul Olav Tvete <paul.tvete@digia.com>